An electro-photographic type image forming apparatus such as a laser printer and LED printer is known in the art. Such apparatus uses a developing cartridge having a developing roller for toner supply. Prior art discloses an image forming apparatus including a drawer unit including a photosensitive drum. A developing cartridge is attached to the drawer unit. Upon attachment of the developing cartridge to the drawer unit, the developing roller and the photosensitive drum contact each other.
Prior art also discloses a drum cartridge and a developing cartridge attachable to the drum cartridge. The drum cartridge includes a photosensitive drum. Upon attachment of the developing cartridge to the drum cartridge, the developing roller and the photosensitive drum contact each other. In a state where the developing cartridge is attached to the drum cartridge, the drum cartridge is attached to an image forming apparatus.
Further, a developing cartridge including a storage medium such as IC chip is known. The storage medium includes an electrical contact surface configured to contact an electrical terminal of an image forming apparatus or an electrical terminal of a drawer unit.